The invention relates to a disk brake for a utility vehicle and to a brake caliper of a disk brake.
Disk brakes of said type are well known. For example, reference may be made to German patent document no. DE 195 15 063 C1, which discloses a generic axial disk brake in which, during a braking operation, a brake lever of a brake-application device acts on a bridge in which there are mounted two brake plungers, said brake plungers being arranged parallel to and spaced apart from one another and having in each case one thrust piece. Here, a lever arm of the brake lever projects into a dome integrally formed on a brake caliper.
A brake pad bearing against the thrust pieces is, during the braking operation, pressed against a brake disk, for which purpose the brake lever is pivoted by a pneumatically or electromechanically actuable tappet such that, via an eccentric which is connected to the brake lever and which is supported on the bridge, the bridge is displaced with the pressure plungers in the direction of the brake disk.
Opposite this, the brake lever is supported in a plain bearing arrangement which is provided on an inner side of the wall of the brake caliper so as to form a caliper head, wherein the wall forms a receiving space for the brake-application device, which brake-application device is inserted through an installation opening situated opposite the wall. The dome into which the lever arm, extending transversely with respect to the brake-application direction, of the brake lever projects is integrally formed with the unipartite brake caliper which is composed of cast iron.
The plain bearing arrangement at the wall side has a receptacle which is of channel-shaped and, in cross section, circular-arc-shaped form and extends transversely with respect to the pivoting direction.
In this receptacle, which is preferably lined with a bearing shell, there is positioned a pivoting body which may be in the form of a separate roller or of a bead integrally formed on the brake lever, which bead is, at least over the pivoting range, of circular-arc-shaped form corresponding to the curvature of the receptacle.
Here, a receptacle is formed into the caliper head, for which purpose, in the brake caliper, there is provided a lateral machining opening through which a machining tool, for example a milling tool, can be inserted.
For accurately positioned displacement of the bridge, exact positioning of the brake lever is necessary, which, with the hitherto known design, is however not ensured but is at best purely incidental and not permanent.
This can self-evidently give rise to problems with regard to the operational reliability of the brake-application device, because a small displacement of the brake lever transversely with respect to the pivoting direction leads to a changed engagement on the bridge, which adversely affects the operating behavior thereof.
Furthermore, there is the risk of uncontrolled loading of components involved, which components ultimately have an influence on the service life, that is to say the service life is reduced in relation to a situation with permanently exact guidance.
German patent document no. DE 10 2012 108 689 A1 has disclosed a radial disk brake in which a lever arm of the brake lever extends approximately parallel to the axis of rotation of the brake disk. For securing the brake lever in terms of displacement, securing elements are fastened to both sides of a pivoting body which is in the form of a roller, one of which securing elements is in the form of a shift fork which is operatively connected to a readjustment device, whereas the other securing element is formed from a holding plate.
The two securing elements are supported both on the brake lever and on a caliper head of the brake caliper, such that the pivoting body, and likewise the brake lever, are in effect clamped. It is however a disadvantage here that both securing elements bear with a relatively large contact surface against the caliper head, such that, during the pivoting of the brake lever, corresponding friction forces must be overcome.
From German patent document no. DE 10 2012 108 670 A1, it is known, for the purposes of securing the brake lever in terms of displacement, for parallel keys to be provided which bear against the lever arm of the brake lever outside a bearing arrangement on the brake caliper side and between which the lever arm is guided.
The invention is based on the object of further developing a disk brake and a brake caliper of the generic type such that the functional and operational reliability of the disk brake is improved with little outlay in terms of design and manufacture.
The invention ensures that the brake lever permanently assumes a defined position, that is to say a displacement perpendicular to the pivoting direction is ruled out.
This positive guidance prevents impairments in the operating behavior of the brake-application and considerably improves functional reliability.
In particular, the bridge is no longer subjected to load insofar as no lateral misalignment which could be attributed to a corresponding uncontrolled movement of the brake lever is possible. This is associated with a considerable lengthening of the service life of the components involved.
Since the lever is secured very close to the center of rotation of the lever, good hysteresis is promoted. Here, only the securing element according to the invention has to be attached as an additional component, whereas the other functional parts can be used in the known form, modified only insofar as a corresponding configuration for receiving the securing element must be provided.
For this purpose, both in the brake lever and in the receptacle of the caliper head for the mounting of the pivoting body, there is provided in each case one slot into which the securing element engages. It is also conceivable for the receptacle to be provided in at least one bearing block which is connected, as a separate component, to the wall of the brake caliper, wherein then, the slot is formed into the bearing block. In the case of two bearing blocks arranged adjacent to one another, the slot may be formed by a selected spacing between the two bearing blocks.
Said securing element may be in the form of a disk, parallel key or ring-shaped disk which engages into the slots adapted thereto, wherein, in one design variant, the ring-shaped disk is fastened to the pivoting body formed as a roller, and in another variant, said ring-shaped disk is recessed into a bead which forms the pivoting body and which is integrally formed on the brake lever, wherein said disk projects in each case into the slot of the caliper head or of the brake lever.
The disk, which may also have a shape which deviates from that of a circle, is very easy to produce, and exhibits very little wear in particular if it is composed of a hardened steel.
Instead of a separate securing element, said securing element may be integrally formed in the manner of a pin or disk on the bead or on the roller.
The mutually oppositely situated slots are preferably of circular-arc-shaped profile, wherein the imaginary center of rotation corresponds to that of the pivoting body or of the receptacle.
Thus, very simple machining of the caliper head is possible, because a milling cutter merely has to be inserted through the lateral machining opening of the brake caliper.
The dimensioning both of the receptacle, that is to say the radius of curvature thereof, and of the radius of curvature of the slot may be kept relatively small, such that the lateral machining opening, adapted thereto, can also be kept correspondingly small in terms of its diameter.
This serves primarily to ensure the stability of the brake caliper, because the machining opening, in principle, forms a point of weakened strength, which is thus reduced to an acceptable dimension.
Furthermore, the securing element and the recesses in the caliper head and brake lever, that is to say said slots, are dimensioned in terms of their width or thickness such that the securing element duly lies therein substantially without play but can be inserted easily and without problems.
Furthermore, multiple securing elements may be provided if required.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.